Bottle coating machine



y 1966 w. P. MAYER ETAL 3,253,943

BOTTLE COATING MACHINE Filed March 4, 1963 s Sheets-Sheet 1 miil E iINVENTORS WALTER F. MAYER STANLEY H. RICHARDSON A T TORNEV y 1, 1966 w.P. MAYER ETAL 3,253,943

BOTTLE COATING MACHINE Filed March 4, 1963 3 Sheets-Sheet 2 WALTER F.MKY E R STANLEY H. RICHARDSON A T TORNEV May 31, 1966 w. P. MAYER ETAL3,253,943

BOTTLE COATING MACHINE Filed March 4, 1963 3 Sheets-Sheet 5 TIMERINVENTORS.

WALTER P. MAYER STANLEY H. RICHARDSON BY flan/Wt am ATTORNEY UnitedStates Patent 3,253,943 BOTTLE COATING MACHINE Walter P. Mayer, Lebanon,and Stanley H. Richardson,

Millington, N.J., assignors to Union Carbide Corporation, a corporationof New York Filed Mar. 4, 1963, Ser. No. 262,501 Claims. (Cl. 117-94)This invention relates to bottle coating, and more particularly tomethod and apparatus for coating plastic bottles.

There are many products not packagable in polyethylene. Oxygen and manysolvents and essential oils permeate polyethylene bottles giving rise tovolume, flavor or odor loss or product damage by oxidation. In manycases, these problems can be eliminated by applying a barrier coating onthe surface of the polyethylene.

The main object of the present invention is to provide method andapparatus for applying such coating to bottles.

Because a polyethylene bottle is a low-cost, disposable package, thecoating costs must be kept low. It is also desirable to provide an innerand outer coated bottle. This demands a fast, simple, versatile processwhich produces a quality coating.

Unique features of our coating process are:

(1) Use of an arcuate dipping-draining motion: This avoids tears andpuddles which result in coating imperfections and slow drying. Thebottle neck becomes the final drain point for the coating.

(2) Rapid setting and drying to give a uniform continuous coating byblowing air into the bottle while heating the outside of the bottle.

(3) Holding the bottle by the outer edge of the neck by means of ahollow work holder, thereby allowing simultaneous inner and outercoating by coating and draining all bottle surfaces in one step.

(4) Drying of the entire inner and outer bottle surface except at thepoints of contact with the work holder by controlling drying conditions.The bottle is thus dry enough to be handled for removal from the Workholder, but the outer neck area remains wet so as to prevent adhesion ofthe bottle to the work holder.

In our dip process, the bottles are held by the neck. Any size or shapebottle having the same neck finish can be handled by a single size workholder. This allows very low work holder inventory and permits differentbottles with the same neck finish to be coated interchangeably on thesame line.

Inner and outer coating of bottles by spray requires at least twoseparate coating steps. The bottles, held by the base, would first beinternally sprayed, force dried, and then transferred to another workholder holding the bottles by the neck forthe outer coat, followed by asecond drying step. The dipping process does all these operations in onestep.

Our dip process is also more versatile than spraying. Many bottle typessuch as pinch-waist, oval, hollow handle and offset neck are verydifficult to line by spray. These bottles are no particular problem toour dip process provided the shoulder has suflicient pitch to allowdrainage.

Another advantage of the dip process is its simplicity, allowingoperation by unskilled workers. There is little to go wrong once coatingviscosity is adjusted and oven temperatures are set. Spraying,particularly internal, is more critical in that spray pattern and volumemust be carefully adjusted and maintained for a satisfactory coatingjob.

The dipping process can produce coated bottles at least as fast as mostcommercial spray or flushing machines.

The limiting factor may be the rate at which the bottles can be loadedand unloaded.

In the drawings:

FIG. 1 is a side elevation of the preferred embodiment of apparatusaccording to, and for carrying out the method of, the present invention;

FIG. 2. is a plan of the machine shown in FIG. 1;

FIG. 3 is an end elevation of the same;

FIG. 4 is our end elevation of a modification.

FIG. 5 is a side elevation showing in greater detail the liquid fillingstation in the modification illustrated in FIG. 4; and

FIG. 6 is a schematic electrical diagram of the electrical controlcircuitry comprised in .a system according to the present inventionillustrated in FIG. 4.

The machine consists of two parallel conveyor chains 10 between whichare suspended at equally spaced intervals cross-bars 12. Each cross-barsupports a series of bottle holders 14. Spacing between cross-bars andbetween bottle holders is determined by the size of the bottles to becoated.

In operation the bottles, held by the outside edge of the neck, arecarried into a dip tank 16 where the bottle is submerged and allowed tofill with coating solution. The bottles emerge from the tank orientedneck down with their longitudinal axis about 20 above horizontal. Thisallows most of the coating to flow into drip pans 18 for recycle, andallows the inner and outer surfaces of the base to drain free of largedroplets or puddles. Next the bottles assume an inverted position,allowing the remaining coating to drain, and leaving the bottle coatedoverall with a uniform wet film.

Setting and drying of the coating is achieved by conveying the bottlesinto an oven 20 where the outsidesv of the bottles are heated whiletheinsides are purged with air issuing from a series of air jets 22.Best quality of the inner coating is obtained when the purging air is atroom temperature rather than heated. Ventilation of the inside of thebottle removes solvent vapors as they are generated and avoidsrecondensation on the bottle wall with resultant wash down of coating.

The conveyor moves intermittently by means of an indexing mechanism. Theconveyor speed, while in motion, is about 0.25 foot per second. The timeinterval during which the conveyor is stopped is controlled by anadjustable timer and usually ranges from about 8 to 16 seconds,depending on the time needed to fill a submerged bottle.

Each time the conveyor stops, one bank of bottles is submerged in thecoating, and each bottle in the drying oven is stopped directly over anair jet. By means of a solenoid valve 24, the ventilating air is offwhile the bottles are moving, and on while the bottles are stopped. Thisprevents the air blast from distorting the coating on the exposedshoulders of moving bottles. A throttling valve 26, allows control ofvolume of air fed to the air jets. A manifold system 28 supplies air tothe jets.

Indexing is triggered when a moving cross-bar depresses a pulse-typemicroswitch 30. (A pulse-type switch, when depressed, closes momentarilyand reopens.) The pulse causes timer 32 to start timing: clutch 34deenergizes, brake 36 energizes (conveyor stops), solenoid air valveopens (turns air jets on).

Timer times out: clutch energizes, brake deenergizes (conveyor moves),solenoid air valve closes (turns air jets off). Conveyor moves untilnext crossbar depresses microswitch and repeats cycle.

One of the problems in simultaneously coating the inner and outersurfaces of a' bottle is that of holding the bottle through the dippingand drying steps without ruining the appearance of the coating at thepoint of contact, or adhering the bottle to the work holder during thedrying.

This problem is largly overcome by adjusting drying conditions such thatthe entire bottle is dried except for the threaded area of the neck incontact with the work holder. This area remains wet longer than the restof the bottle because solvent is trapped by the work holder. On leavingthe drying oven, the bottle, dry enough to handle, is removed from thework holder and transferred to a curing oven; The coating on the nowexposed threaded area flows out and dries quickly.

The emptied work holder can be immediately refilled with another bottleto repeat the dip cycle or passed through a cleaning station beforerefilling. In continuous running, inline cleaning of work holdersappears necessary. The work holders 14 are preferably of the screw-in tye.

in cases where only the outside of the bottle is to be coated, thecoating level is adjusted so that the bottle is submerged only so far asto cover the shoulders. The bottle is then drained and dried as shown inFIGURE 1 except that the air jets may be turned off and the conveyorneed not be indexed. Conveyor speed is adjusted to allow drying withinthe length of oven available.

Where only the inside of the bottle is to be coated, the dip tank isemptied and the dipping end of the machine is equipped with a fillingstation so that the bottles are pressure-filled at the same point atwhich they would otherwise be filled by submersion in the coating. Inthat case, the dip tank acts as a sump from which coating is recycled tothe filling device pump. After being filled, the drain and dryingtechnique would be the same as described earlier.

Pressure filling can also be used to speed the indexing cycle when usedin place of filling by submersion.

Very large containers in the half-gallon size and larger are somewhatawkward to. dip coat in the manner described previously. For thesecontainers, it is more convenient to coat the outside by flowing orflooding, and the inside by flushing thereby coating the bottle withoutactually submerging it or filling it. The coating is then drained anddried in the same way described earlier.

Technique for automatic flow-coating and/ or flush coating on thedipping machine has been successfully carried out. When it is desired tocoat the interior of the bottles without necessarily coating the outsidethereof, the form shown in FIGURE 4 is employed. The coating isconsirable since the lip surface sometimes is poorly treated and coatingcan become loosened in the course of un-.

, is done while the conveyor is moving the bottle from one tained in asupply tank into which depends the inlet pipe 42 of an air operatedpositive displacement pump 44. The pump outlet pipe 46 passes through aline strainer 47 to a coating manifold 48 for filler tubes 50, eachhaving a solenoid valve 52. The conveyor moves until cross-bar 54 tripsthe limit switch 56. Indexing timer 58 beings timing, stops the conveyorand opens solenoid valve 24 which feeds ventilating air to bottles inthe oven.

Simultaneously fill timer 60 begins timing, and opens coating solenoidvalves 52. Pressure in coating manifold 48 drops. Pump 44 begins pumpingthe coating through filler tubes 50 into thebottle in the fill position.

The fill timer 60 times out, being set to allow bottles to fill full inabout 6 seconds. Coating solenoid valves 52 close, pressure in coatingmanifold 48 builds up and stops the pump 44.

The indexing timer. times out after about 13 seconds. The conveyor movesuntil next cross bar 54 trips the limit switch 56. Bottles in fillposition move up and invert to drain position. Coating drains frombottles into drain pan 62, from which it flows through tube 65 back intocoating supply tank 40.

Drips of coating which form on the lip of the bottle while draining mustbe removed. This should preferably be done after the bottle hascompleted draining but before the coating has set. If-this is neglected,the coating dries to hardened droplets on the lip of the bottle whichprevent proper seating of the bottle cap causing leakage. Furthermore,any coating on the lip of the bottle is undeair jet to the next.

The wiper consists of a cup 64 into which is cemented a disk of opencell resilient, urethane foam. A manifold 66 feeds solvent such as waterinto the base of cup 64. Solvent diffuses upward through the foam andflows out through the surface, overflowing into a larger cup 68. Fromhere thewater flows through an outlet tube 70 into wash-water sump 72provided with a recycle pump 74 for solvent feed line 76.

The bottle lip passes over the surface of the flooded foam. Rubbingaction of the foam removes partly dried coating which is flushed away bythe water. Thus our wiper is self cleaning.

After passing over the flooded foam the bottle lip is dripping withwater containing a very small amount of coating residue. This is removedby passing through a second'or dry wiper 78. This is merely a slab ofurethane foam set in a metal support. Th dry Wiper actually remainsmoist and pliable from Water carried over from the flooded wiper. Thisprevents drying out and crusting over, which destroys wiping action.

FIG. 5 shows a filler tube of FIG. 4 in greater detail with a bottlepositioned beneath it. The tube is close enough to the bottle mouth toeffect injection of coating fluid into the bottle while being clear ofthe bottle to permit its passage.

FIG. 6 illustrates the control-scheme to effect operation of the coatingmachine as depicted in FIG. 4. The closing of line switch SW-4 andsafety switch SW-3 energizes movement of the conveyor until cross-bar 54depresses limit switch 56 thus activating timer 58. Contacts in timer 58open during a timing and timed out cycle causing clutch-brake controllerCBC to deenergize the clutch C' and simultaneously activate the brake B,thereby stopping or indexing the conveyor. A motor, M, which providesthe mechanical drive for the conveyor remains running throughout theentire cycle. During the timing sequences, timer 58 supplies current toclose solenoid relay R-1 and to open solenoid valve SVA which feeds airto the ventillating air manifold. When relay R-1 closes it activatestimer 60. While timing, timer supplies current to six solenoid valvesSVC-l, --2, 3, 4, -5, and 6, supplying fluid to the filler tubes50. Whentimer 60 times out, it supplies current to solenoid relay R-2 whichallows timer 58 to reset after a one-half second time delay ondeenergization.

Toggle switches SWC-l, 2, 3, 4, 5, and 6 permit individual solenoidvalves to be manually shut off.

Push button PB permits manual start of the timer cycle from the controlpanel.

Toggle switch SW-2, when open, permits continuous conveyor movementwithout indexing.

Toggle switch SW-S allows the clutch to be deenergized independently,thereby allowing the machine to be put through the bottle-fill cyclewithout conveyor movement.

What is claimed is:

1. Method of coating bottles, which comprises holding the bottles by theoutside edge of the neck thereof, conveying the bottles in suspendedrelation through an arcuate path at a coating station first down toreceive coat ing solution and then up to drain solution therefrom, thenin an inverted position through a drying station where the bottle isheated.

2. Method as claimed in claim 1, in which the bottle being conveyed downin said arcuate path is submerged in the coating solution to fill theinterior thereof, and the jected to an air jet purge.

5. Apparatus for coating bottles, which comprises means for holding thebottles by the outside edge of the.

neck thereof, means for conveying the bottles in suspended relationthrough an arcuate path at a coating station first down to receivecoating solution and then up to drain solution therefrom, then in aninverted position through a drying station where the bottle is heated.

6. Apparatus as claimed in claim 5, in combination .with a tankcontaining coating solution in which the bottle being conveyed down insaid arcuate path is submerged to fill the interior thereof, and fromwhich the filled bottle emerges and drains as the bottle is conveyed upin said arcuate path.

7. Apparatus as claimed in claim 5, in combination with means forpassing the bottle from said arcuate path upwardly along an inclinedpath in which the bottle with the neck down is inclined at an acuteangle to the horizontal.

8. Apparatus as claimed in claim 5, in combination with an air jet insaid drying station for subjecting the interior of the bottle beingheated to a purging operation.

9. Method of coating bottles, which comprises'holding the bottles by theoutside edge of the neck thereof, conveying the held bottles to afilling station in suspended relation to receive coating solution,inverting the coated bottles while conveying them in a draining stationto discharge excess coating solution, conveying the discharged bottlesthrough a drying station, and heating the conveyed bottles in saiddrying station.

10. Method as claimed in claim 9, in which the coating solution ispumped through the so held necks of said bottles into the interiorthereof at said filling station in sufi'icient quantity to fill thebottom portion of the bottle, and to coat the remaining upper portion ofthe bottle as the excess is discharged at said draining station.

11. Method as claimed in claim 9in which the necks of the inverteddischarged bottles are passed over a porous wiper containing solvent forsaid coating before the bottles leave said drying station.

12. Method of coating bottles, which comprises feeding the bottles intoengagement of the outside edge of the neck thereof with a holder,conveying said holder with the bottle suspended therebelow to a fillingstation to receive coating solution, conveying said holders to adraining station along an arcuate path with the necks of the bottlestoward the center of curvature and thereby inverting said bottles todischarge excess coating solution, conveying the discharged bottlesthrough a drying station, and heating the conveyed bottles in saiddrying station.

13. Apparatus for coating bottles, which comprises means for holding thebottles by the outside edge of the neck thereof, means for conveying theheld bottles to a filling station in suspended relation to receivecoating so lution, means for inverting the coated bottles while conveying them in a draining station to discharge excess coating solution,means for conveying the discharged bottles through a drying station, andan oven at said drying station for heating the conveyed bottles.

14. Apparatus as claimed in claim 13 in combination with a porous wipercontaining solvent for said coating and engaging the necks of theinverted discharged bottles before they leave said drying oven.

15. Apparatus as claimed in claim 13 in combination with a pump andfiller tubes in the filling station adapted for pumping coating solutioninto the interior of the bottles.

References Cited by the Examiner UNITED STATES PATENTS 1,151,636 8/1915Weis et a1 1l8426 1,602,835 10/ 1926 Reifsnyder 11795 2,411,042 11/1946King et al 118-102 2,892,733 6/1959 Gardner et a1. 11746 2,981,6394/1961 Kachele 117-113 RICHARD D. NEVIUS, Primary Examiner. JOSEPH B.SPENCER, Examiner.

9. METHOD OF COATING BOTTLES, WHICH COMPRISES HOLDING THE BOTTLES BY THEOUTSIDE EDGE OF THE NECK THEREOF, CONVEYING THE HELD BOTTLES TO AFILLING STATION IN SUSPENDED RELATION TO RECEIVE COATING SOLUTION,INVERTING THE COATED BOTTLES WHILE CONVEYING THEM IN A DRAININGSTATIONTO DISCHARGE EXCESS COATING SOLUTION, CONVEYHING THE DISCHARGEDBOTTLES THROUGH A DRYING STATION, AND HEATING THE CONVEYED BOTTLES INSAID DRYING STATION.
 11. METHOD AS CLAIMED IN CLAIM 9 IN WHICH THE NECKSOF THE INVERTED DISCHARGED BOTTLES ARE PASSED OVER A POROUS